Vehicular camera testing using a slanted or staggered target

ABSTRACT

A method of testing a vehicular camera for a vehicular vision system includes providing a vehicular camera suitable for use on a vehicle, with the vehicular camera having a field of view. A collimator is provided that includes an optic and a target. The collimator is positioned in the field of view of the vehicular camera such that the camera images light that reflects off the target and passes through the optic. The target is angled or stepped relative to an image plane of the vehicular camera. Image data is captured with the vehicular camera, with the captured image data being representative of the angled or stepped target. The captured image data is processed, via an image processor, and a defocus of the vehicular camera is estimated based on processing by the processor of the captured image data of the angled or stepped target.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority of U.S. provisional application,Ser. No. 62/878,945, filed Jul. 26, 2019, and U.S. provisionalapplication Ser. No. 62/781,791, filed Dec. 19, 2018, which are herebyincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates generally to a vehicle vision system for avehicle and, more particularly, to a vehicle vision system that utilizesone or more cameras at a vehicle.

BACKGROUND OF THE INVENTION

Use of imaging sensors in vehicle imaging systems is common and known.Examples of such known systems are described in U.S. Pat. Nos.5,949,331; 5,670,935 and/or 5,550,677, which are hereby incorporatedherein by reference in their entireties.

SUMMARY OF THE INVENTION

The present invention provides a testing system for a camera for adriver assistance system or vision system or imaging system for avehicle. The testing system or method measures or estimates the defocusof the camera. The system includes a collimator with an internal opticand target. The target may be angled relative to an image plane of thecamera or include a stepped surface within the view of the optic andcamera. The defocus of the camera may be measured based on image datacaptured of the angled or stepped target.

These and other objects, advantages, purposes and features of thepresent invention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vehicle with a vision system thatincorporates at least a forward camera module;

FIG. 2 is a perspective view of a motorized test system;

FIG. 3 is a perspective view of a test system with multiple optics;

FIG. 4 is a block diagram of a test system with multiple collimators;

FIG. 5 is a block diagram of a test system with a slanted target inaccordance with the present invention;

FIG. 6 is a block diagram of a test system with a staggered target inaccordance with the present invention;

FIGS. 7A and 7B are perspective views of a collimator with multipletargets in accordance with the present invention;

FIGS. 8A and 8B are perspective views of an etched glass target inaccordance with the present invention;

FIG. 9 is a plan view of a of a staircase step collimator in accordancewith the present invention; and

FIG. 10 is an exploded view of the staircase step collimator of FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A vehicle vision system and/or driver assist system and/or objectdetection system and/or alert system operates to capture images exteriorof the vehicle and may process the captured image data to display imagesand to detect objects at or near the vehicle and in the predicted pathof the vehicle, such as to assist a driver of the vehicle in maneuveringthe vehicle in a rearward direction. The vision system includes an imageprocessor or image processing system that is operable to receive imagedata from one or more cameras and provide an output to a display devicefor displaying images representative of the captured image data.Optionally, the vision system may provide display, such as a rearviewdisplay or a top down or bird's eye or surround view display or thelike.

Referring now to the drawings and the illustrative embodiments depictedtherein, a vision system 10 for a vehicle 12 includes at least oneexterior viewing imaging sensor or camera, such as a forward viewingimaging sensor or camera, which may be disposed at and behind thewindshield 14 of the vehicle and viewing forward through the windshieldso as to capture image data representative of the scene occurringforward of the vehicle (FIG. 1). Optionally, the system may includemultiple exterior viewing imaging sensors or cameras, such as a forwardviewing camera at the front of the vehicle, and a sideward/rearwardviewing camera at respective sides of the vehicle, and a rearwardviewing camera at the rear of the vehicle, which capture images exteriorof the vehicle. The camera or cameras each include a lens for focusingimages at or onto an imaging array or imaging plane or imager of thecamera. Optionally, the forward viewing camera may be disposed at thewindshield of the vehicle and view through the windshield and forward ofthe vehicle, such as for a machine vision system (such as for trafficsign recognition, headlamp control, pedestrian detection, collisionavoidance, lane marker detection and/or the like). The vision system 10includes a control or electronic control unit (ECU) or processor that isoperable to process image data captured by the camera or cameras and maydetect objects or the like and/or provide displayed images at a displaydevice for viewing by the driver of the vehicle. The data transfer orsignal communication from the camera to the ECU may comprise anysuitable data or communication link, such as a vehicle network bus orthe like of the equipped vehicle.

The system or method of the present invention estimates or measures thedefocus of a vehicular camera. Typically, the ability to determine aposition of a lens (i.e., an optic) in relation to an imager isaccomplished by one of three methods. First, as illustrated in FIG. 2,the defocus may be estimated by utilizing a motorized stage to move atarget to different distances in relation to the optic. This methodincreases cycle time, requires a complex motorized system, incurssignificant equipment costs, and requires moving parts to estimatedefocus. Second, as illustrated in FIG. 3, the defocus may be estimatedby using multiple collimators with targets located in differentpositions in relation to the optic. This method also increases cycletime due to measuring with multiple optics, requires a complex motorizedsystem, incurs significant equipment costs, and requires moving parts toestimate defocus. Third, as illustrated in FIG. 4, the defocus may beestimated by using different optics to simulate different distances.This method increases costs due to the multiple collimators, increasesthe complexity of the collimators, and potentially decreases accuracy(due to measuring different collimators in different locations). Theseprocesses are commonly referred to as measuring or estimating thedefocus of a camera. That is, these processes determine how far off peakthe finished camera is.

The system or method of the present invention (FIGS. 5 and 6) uses asingle collimator and positions an internal target at differentdistances relative to the optic. Thus, only a single collimator withoutmoving parts is used. This allows for reduced capital expenditures,reduced collimator complexity, and increases accuracy due to measuringwith only a single collimator at a single location. Additionally, thepresent invention provides the ability to measure defocus in eachcollimator location and does not require moving parts to estimate ormeasure defocus. Image data captured by the camera with the target ortargets present in the field of view of the camera is processed (via animage processor) to determine or estimate the degree of focus or defocusof the camera at the target.

Referring now to FIG. 5, a camera 510 has a field of view that includesa collimator 520. The collimator 520 includes a lens or optic 530 andtarget 540. The target 540 is angled relative to an image plane of thecamera 510. For example, the target 540 may be angled at 45 degreesrelative to the image plane of the camera 510. The angling of the target540 results in one edge of the target 540 being closer to the optic 530(and camera 510) than the opposite edge. For example, if the distancebetween the optic 530 and the center of the target 540 is x, one edgemay be x−5 mm while the opposite edge is x+5 mm. Thus, the camera 510may image the target 540 at a plurality of distances without moving thecamera 510, the collimator 520, the optic 530, or the target 540.

In another implementation, a camera 610 has a field of view thatincludes a collimator 620 (FIG. 6). The collimator 620 includes a lensor optic 630 and target 640. The target 640 includes a stepped surfacethat is within the field of view of the camera 610. The target 640 mayinclude a plurality of steps, each step a different distance from theoptic 630 and camera 610. For example, the target 640 may include 3steps. In that example, if the distance between the optic 630 and thecenter step is x, one step may be x−5 mm while the third step is x+5 mm.The target 640 may include any number of steps. The steps may maintain aregular distance from one step to the next or an irregular distance.Thus, the camera 610 may image the target 640 at a plurality ofdistances without moving the camera 610, the collimator 620, the optic630, or the target 640.

In some examples, the system includes multiple targets 710 to increasethe measurement window. That is, additional targets may be added beforeand/or after a center target (FIGS. 7A and 7B). For example, the systemmay include a total of seven targets 710, and the center target may haveone, two, or three targets in front of it (i.e., +1, +2, and +3) andone, two, or three targets behind it (i.e., −1, −2, and −3).

Optionally, and with reference to FIG. 8A, the system may include glasstargets with patterns laser etched onto the glass to improveblack-to-white transition, with each stacked as illustrated in FIGS. 7Aand 7B. The glass targets may have any diameter. For example, thetargets may have a one inch diameter. Each target may have a differentpattern thus giving the collimator multiple patterns at differentdistances. In some examples, four different patterns are used: a centertarget pattern and three other target patterns equally spaced around thecenter target pattern (FIG. 8A). For example, the center target 810 mayhave a unique pattern, the +1 and −1 targets 812 a, 812 b may share apattern, the +2 and −2 targets 814 a, 814 b may share a pattern, and the+3 and −3 targets 816 a, 816 b may share a pattern for a total of fourseparate patterns. The patterns may include interlocking squares orrectangles that create high contrast (FIG. 8B).

Referring now to FIG. 9, in another example, the target may include astaircase collimator 900 with multiple (e.g., seven) targets. That is,the target may include multiple staircase “steps” 900, each with asingle target disposed within an opening 1010 of the step (FIG. 10). Thetarget disposed within each opening of each step may include opticalglass (e.g., a quarter inch in diameter optical target). One step may bea center target step 1020 while the remaining steps are non-center steps1030. The center step 1020 may include the opening 1010 in the center ofthe step. Each non-center step 1030 may include the opening 1010 for thetarget around the perimeter of the step, and each step may be rotatedwith respect to the other non-center steps so that the camera views eachtarget through a single piece of glass (as opposed to multiple pieces ofglass for multiple targets). For example, there may be seven steps 900(and therefore seven targets). For example, six of the non-center steps1030 may be each offset 60 degrees from the previous to create a ring oftargets and the seventh may be disposed in the center of the step (i.e.,in the center of the ring of six targets).

Thus, the system of the present invention includes a single collimatorwithout moving parts and with one or more targets that measures thedefocus of a camera. The collimator may include a light emitting diode(LED) light source. High precision tooling (e.g., Fullcut Mill (FCM) 3)may be used to improve stability. Image data captured by the camera withthe target or targets present in the field of view of the camera isprocessed (via an image processor) to determine the degree of focus ordefocus of the camera at the target.

The system includes an image processor operable to process image datacaptured by the camera or cameras. For example, the image processor maycomprise an image processing chip selected from the EYEQ family of imageprocessing chips available from Mobileye Vision Technologies Ltd. ofJerusalem, Israel, and may include object detection software (such asthe types described in U.S. Pat. Nos. 7,855,755; 7,720,580 and/or7,038,577, which are hereby incorporated herein by reference in theirentireties), and may analyze image data to detect vehicles and/or otherobjects. The system may utilize aspects of the systems described in U.S.Publication No. US-2018-0373944, which is hereby incorporated herein byreference in its entirety.

For example, the vision system and/or processing and/or camera and/orcircuitry may utilize aspects described in U.S. Pat. Nos. 9,233,641;9,146,898; 9,174,574; 9,090,234; 9,077,098; 8,818,042; 8,886,401;9,077,962; 9,068,390; 9,140,789; 9,092,986; 9,205,776; 8,917,169;8,694,224; 7,005,974; 5,760,962; 5,877,897; 5,796,094; 5,949,331;6,222,447; 6,302,545; 6,396,397; 6,498,620; 6,523,964; 6,611,202;6,201,642; 6,690,268; 6,717,610; 6,757,109; 6,802,617; 6,806,452;6,822,563; 6,891,563; 6,946,978; 7,859,565; 5,550,677; 5,670,935;6,636,258; 7,145,519; 7,161,616; 7,230,640; 7,248,283; 7,295,229;7,301,466; 7,592,928; 7,881,496; 7,720,580; 7,038,577; 6,882,287;5,929,786 and/or 5,786,772, and/or U.S. Publication Nos.US-2014-0340510; US-2014-0313339; US-2014-0347486; US-2014-0320658;US-2014-0336876; US-2014-0307095; US-2014-0327774; US-2014-0327772;US-2014-0320636; US-2014-0293057; US-2014-0309884; US-2014-0226012;US-2014-0293042; US-2014-0218535; US-2014-0218535; US-2014-0247354;US-2014-0247355; US-2014-0247352; US-2014-0232869; US-2014-0211009;US-2014-0160276; US-2014-0168437; US-2014-0168415; US-2014-0160291;US-2014-0152825; US-2014-0139676; US-2014-0138140; US-2014-0104426;US-2014-0098229; US-2014-0085472; US-2014-0067206; US-2014-0049646;US-2014-0052340; US-2014-0025240; US-2014-0028852; US-2014-005907;US-2013-0314503; US-2013-0298866; US-2013-0222593; US-2013-0300869;US-2013-0278769; US-2013-0258077; US-2013-0258077; US-2013-0242099;US-2013-0215271; US-2013-0141578 and/or US-2013-0002873, which are allhereby incorporated herein by reference in their entireties. The systemmay communicate with other communication systems via any suitable means,such as by utilizing aspects of the systems described in InternationalPublication Nos. WO 2010/144900; WO 2013/043661 and/or WO 2013/081985,and/or U.S. Pat. No. 9,126,525, which are hereby incorporated herein byreference in their entireties.

Changes and modifications in the specifically described embodiments canbe carried out without departing from the principles of the invention,which is intended to be limited only by the scope of the appendedclaims, as interpreted according to the principles of patent lawincluding the doctrine of equivalents.

The invention claimed is:
 1. A method of testing a vehicular camera fora vehicular vision system, the method comprising: providing a vehicularcamera configured for use on a vehicle, wherein the vehicular camera hasa field of view; providing a collimator assembly, the collimatorassembly comprising an optic fixedly disposed within the collimatorassembly and a target fixedly disposed within the collimator assembly;positioning the collimator assembly in the field of view of thevehicular camera such that the vehicular camera images light that hasreflected off the target and that has passed through the optic and suchthat a longitudinal axis of the collimator assembly is aligned with aprincipal axis of the field of view of the vehicular camera, wherein,with the collimator assembly positioned in the field of view of thevehicular camera, the optic is perpendicular to the principal axis ofthe field of view of the vehicular camera and the target is angledrelative to the optic and the image plane of the vehicular camera;capturing image data with the vehicular camera, wherein the capturedimage data is representative of the angled target; processing, via animage processor, the image data captured by the vehicular camera; andresponsive to processing by the image processor of the image datacaptured by the vehicular camera, estimating a defocus of the vehicularcamera.
 2. The method of claim 1, wherein the angled target is angled at45 degrees relative to the image plane of the vehicular camera.
 3. Themethod of claim 1, wherein estimating the defocus of the vehicularcamera comprises estimating the defocus of the vehicular camera at aplurality of positions on the angled target, each position at adifferent distance from the optic.
 4. The method of claim 3, wherein thedefocus of the vehicular camera is estimated from three positions. 5.The method of claim 1, wherein at least some of the light that hasreflected off the target is emitted by a light emitting diode disposedat the collimator assembly.
 6. A method of testing a vehicular camerafor a vehicular vision system, the method comprising: providing avehicular camera suitable for use on a vehicle, wherein the vehicularcamera has a field of view; providing a collimator comprising an opticfixedly disposed within the collimator and a target fixedly disposedwithin the collimator; positioning the collimator in the field of viewof the vehicular camera such that the vehicular camera images light thatreflects off the target and passes through the optic and such that alongitudinal axis of the collimator is aligned with a principal axis ofthe field of view of the vehicular camera, wherein the optic isperpendicular to the principal axis of the field of view of thevehicular camera and the target is angled at 45 degrees relative to theoptic and the image plane of the vehicular camera; capturing image datawith the vehicular camera, wherein the captured image data isrepresentative of the angled target; processing, via an image processor,image data captured by the vehicular camera; and responsive toprocessing by the image processor of image data captured by thevehicular camera, estimating a defocus of the vehicular camera at aplurality of positions on the angled target, each position at adifferent distance from the optic.
 7. The method of claim 6, wherein theplurality of positions comprises three positions.
 8. The method of claim7, wherein the three positions comprises a first position, a secondposition, and a third position, and wherein the first position is atleast five millimeters closer to the camera than the second position andwherein the second position is at least five millimeters closer to thecamera than the third position.
 9. The method of claim 6, wherein atleast some of the light that has reflected off the target is emitted bya light emitting diode disposed at the collimator.